Rolling mills



June 23, 1970 H. L. F. BOND 3,516,276

ROLLING MILLS Filed June 6, 1967 5 Sheets-Sheet 1 INVENTOR HARRY LEBOND H S ATTORNEY June 23,1970 H. L. F. BOND 3,516,276

' I ROLLING MILLS Filed June 6. 1967 5 Sheets-Sheet 2 FIG. 2.

INVENTOR HARRY L.F BOND HI ATTORNEY June 23, 1970 H. L. F. BOND 3,515,275

' momma mus Filed June 6. 1967 5 Sheets-Sheet '5 INVENTOR HARRY LEBOND BY jl cl fl ATTORNEY June 23, 1970 H. L. F. BOND 3,516,276

' ROLLING MILLS Filed June 6, 1967 5 Sheets-Sheet 4 INVENTOR HARRY L.F BOND HIS ATTORNEY June 23, 1970 H. F. BOND 3,515,276

ROLLING MILLS Filed June 6. 1967 5 Sheets-Sheet 5 INVENTOR HARRY L.F. BOND B Y j United States Patent 3,516,276 7 ROLLING MILLS Harry Laurence Fred Bond, Hathersage, near Sheffield, England, assignor to Davy and United Engineering Company Limited, Sheffield, England Filed June 6, 1967, Ser. No. 643,866 Int. Cl. 1521b 31/04 US. Cl. 72-237 12 Claims ABSTRACT OF THE DISCLOSURE A rolling mill stand having supports which include fixed spacer blocks interposed between the bearing chocks at each end of two load transferring rolls such as the two rolls of a Z-high mill or the back-up rolls of a 4-high mill. Bolts are provided for clamping the chocks onto the spacer blocks and the spacer blocks may be varied in length by adjustable wedges to adjust the spacing of the load transferring rolls.

This invention relates to rolling mill stands, both of the 2-high and the 4-high type.

There have been numerous prior suggestions for designs of stands, in which there is no conventional housing, the upper and lower chocks being bolted or otherwise held together. In this arrangement, ditficulty has been experienced in providing a mechanism giving easy adjustment of the roll gap, without over complicating the stand and making it prohibitively expensive.

In the present invention, a rolling mill stand has rolls carried at their ends in bearing chocks, fixed spacer blocks interposed between the bearing chocks at each end of the rolls and including adjustment means carried by each block to vary the effective length thereof between the chocks, and means acting on the chocks at each end of the rolls to force the chocks into engagement with the blocks and to hold the chocks to the blocks, the stand being solely supported by the blocks.

This construction enables a relatively simple and inexpensive rolling mill stand to be produced with easy adjustment of the roll gap. In addition, it leads to the use of adjustment means which varies the roll gap about a constant plane, thereby maintaining the pass-line constant.

The means acting on the chocks to force them into en gagement with the blocks are preferably hydraulically operated, in which case coarse control of the roll gap may be effected by the adjustment means and fine control by the hydraulic operation.

The invention will be more readily understood by way of example from the following description of rolling mill stands in accordance therewith, reference being made to the the drawings accompanying the provisional specification (FIGS. 1 to 3) and to the accompanying drawings (FIGS. 4 and 5), in which:

FIG. 1 is a vertical section through one form of a rolling mill,

FIG. 2 is a vertical section through an alternative form of rolling mill,

FIG. 3 is a vertical section through a rod mill,

FIG. 4 is an end view, partly in section of a preferred form of rod mill, and

FIG. 5 to a view of the drive side of the mill of FIG. 4.

FIG. 1 shows one end of a rolling mill having four supports, of which two are shown at 12 and 13, each support comprising a central block 14 mounted on a foot 14A. Upper and lower back-up chocks 15, 16 having bearings 17, 18 for upper and lower back-up rolls respectively are T-shaped and have arms 19 vertically overlapping the blocks 14, above and below respectively, and a central stern portion 20 extending between the blocks 14. Upper 3,516,276 Patented June 23, 1970 and lower work roll chocks 21, 22 for carrying the upper and lower work rolls 23, 24 are positioned between the blocks 14 and between the upper and lower backup chocks. In between each arm 19 and its adjacent block 14 is provided bearing means 25 each comprising a pair of spaced cylindrical rollers 26 engaging in part-cylindrical recesses in bearing blocks 27, 23. The axes 30 of the rollers 26 lie in the same horizontal plane as the axes 31 of their associated back-up rolls but normal to those axes, thus allowing the chocks to pivot about the axes 30. This allows roll bending under rolling load without the need for self aligning bearings in the chocks. The inner surface of each block 27 is of wedge form and engages a correspondingly wedge surface on a wedge member 32 which is adjustable horizontally so as to vary the distance between the block 14 and arm 19 and thus provide an adjustment of the roll gap. Preferably the lower wedges are used for coarse adjustments of roll gap and the upper wedges may be controllable by an automatic gauge control system of known form during rolling. Alternatively coarse adjustment of the roll gap may be provided by inserting packers between bearing means 25 and blocks 14. This adjustment could alternatively be of some other form such as screws. In place of the roller bearing 25, a ball bearing with spherical seatings may be employed.

At each side of the rolls a bolt 33 passes through bores in the arms 19 of the bearings 25, slots in the wedges 32 and a bore in the central block 14; the upper end of the bolt is threaded into a nut 34 engaging the upper surface of the upper back-up chock 15 while the lower end of the bolt carries a piston 35 slidable in a cylinder 36 secured to the lower back-up chock 19; hydraulic fluid supplied to the upper side of piston 36 tends to stretch the bolt and force the chocks towards one another. A predetermined prestressing force may thus be applied to the chocks and central blocks 14 and this will remain constant even when the wedge members 32 are adjusted during rolling to maintain constant gauge.

The mill shown in FIG. 2 resembles that shown in FIG. 1 and like parts have been given like reference numerals and will not be re-described. The mill of FIG. 2 differs from the mill of FIG. 1 in that the bolts 33 do not pass through the blocks 14, bearing units 25 or wedges 32, but instead are confined to the chocks 15, 16. However, the bolts 33 still urge the chocks towards one another and thus urge the arms 19 into contact with the bearing units 25. The bearing units 25 are the same as those in FIGURE 1 except that there is a single roller 26 since the bolts do not have to pass through the bearings. Between each arm 19 and each bearing 25 is located a fixed wedge member 37. Between the upper wedge members 37 and the chocks 14 are located load cells 38 which measure the applied stress i.e. the difference between the prestressing force applied by the bolts 33 and the rolling load. The load cells in cooperation with pressure transducers measuring pressure applied by the bolts may be used to control the wedge adjustment. With the mill of FIGURE 2 when it is required to change the back-up rolls, the back-up chocks work, roll chocks and bolts can be removed without disturbing the housings, bearings 25 or wedge units.

The mill of FIG. 3 resembles that of FIG. 1 and like parts have been given like reference numerals and will not be described again. The FIG. 3 arrangement shows a rod mill in which the work roll chocks are T-sectioned and bolted directly to the support blocks 14.

A fixed cramp bar may be provided to form a rigid attachment between the two centre blocks 14. In this case the cramp bar need not be adjustable to accommodate different roll sizes. The cramp bar can be fixed and the bottom roll be adjusted to it by the bottom wedges according to its diameter. The top roll can be correspondingly adjusted to suit roll diameter and then gauge can be controlled by the adjustment of one of the wedges. In an alternative form there need be only one wedge unit carried in each centre block on which the top and bottom bearing units 25 would be carried. This would automatically give concentric adjustment of the rolls whilst automatically maintaining a constant pass-line. In a rod mill where only small changes to the roll gap are required the prestressing bolts and cylinders could be replaced by stiff springs.

In another form of mill, not illustrated, particularly applicable to the finishing cages of a rod mill where the difference between maximum and minimum roll sizes is very small, the roll gap adjusting mechanism is provided only on one side of the ill. The upper face of the upper bearing means 25 and the lower face of the lower bearing means 25 would have radiused faces to allow slight tilt of the chock assemblies and thus the chocks could be contrived to hinge apart. By the addition of packers in the side which does not contain the adjusting mechanism this arrangement could accommodate larger variation in roll size.

The preload pressure which is applied to the cylinders is normally maintained constant in excess of anticipated rolling load but can be adjusted in step so that it is always in excess of the rolling load but maintains the load on the adjusting mechanism within a certain nominated range. The preload can be measured either by a pressure transducer connected to the hydraulic cylinder or by mounting a load cell in combination with the bolt under the nut at the upper surface of the top chock. The signal thus obtained is used to control the adjusting mechanism.

FIGS. 4 and 5 illustrate a preferred form of rod mill, which has a general resemblance to the stand of FIG. 3, the same reference numerals being applied to equivalent ,parts. In FIGS. 4 and 5, the rods 33 are reversed, the

hydraulic cylinders 36 being located on top of the upper chock and the lower ends 40 of the rods being held to the lower chock 16 by cotters 41 located in slots 42. However, the principal difference between the stand of FIG. 4 from that of FIG. 3 lies in the mechanism for adjusting the roll gap. In FIG. 4, each of the inwardly projecting stand blocks 14 carries a telescopic, symmetrically operating screw-jack engaging with the opposite surfaces of the arms 19 of the chocks 15, 16. Thus, 'each block 14 has a central bore 43 in which is located a vertical shaft 44 carrying a worm wheel 45 driven by a worm 46. The two ends of the shaft 44 are threaded with opposite hands and mate with plungers 47, 48 which are keyed in the bore 43 and which project upwardly and downwardly respectively out of the block 14 and engaging the arms 19 of the chocks 15, 16.

The four blocks 14 are coupled together by ties 50 extending parallel to the roll axes, but above and below the pass-line 51, as shown in FIG. 5, and by ties 52 on both sides of the mill beyond the roll ends. Each block 14 has an outwardly extending, integral foot 53, the mill being supported by the feet 53 which are held in position on bed plates 55 by bolts 54.

The four worms 46 of the four telescopic screwjacks have a common drive so that the plungers 47, 48 move together either inwardly or outwardly to adjust the separation of the chocks 15, 16 symmetrically about the pass-line 51 which itself remains constant in position. This drive comes from an input drive shaft 56 (FIG. 5) which extends across the mill parallel to the axes of the rolls and carries two mitre gears 57, on the drive side, and 58, on the roll change side. These gears mesh respectively with mitre gears 60 on vertical shafts 61 supported beyond the roll ends and carrying further mitre gears 62 at their upper ends. Each gear 62 meshes firstly with a mitre gear 63 on the shaft of one of the worms 46 on the drive side of the mill, and secondly with a further mitre gear 64 on a shaft 65 which extends across the end of the mill, the two shafts 65 driving the worms 46 at the roll change side through pairs of mitre gears.

The roll necks are carried in self-aligning bearings in the chocks 15, 16 so that bearings permitting the chocks 15, 16 to tilt relative to the housing blocks 14 are not required. As distinct from the stand of FIG. 3,

the prestressing bolts 33 do not pass through the blocks 14 but are confined to bores in the chocks 15, 16.

In operation, the roll gap is set by adjustment of the telescopic screw-jacks carried by the blocks 14. If so desired, the prestress pressure may be reduced to a nominated value, by simple operation of a pressure reducing valve, when it is required to make an adjustment in order to reduce the effort required on the screw-jack system. Alternatively, the roll gap may initially be set approximately by the operation of the telescopic screwjacks carried by the blocks 14, control of the roll gap during operation being effected by adjustment of the pressure of the liquid supplied to the four cylinders 36. As before, this pressure is maintained in excess of the likely rolling load and may be controlled manually to correct for gauge or may be controlled automatically by a dimensional measuring device such as a profile gauge.

The stands shown in the drawings and particularly in FIGS. 4 and 5 have a number of practical and operating advantages. In the first place, the mounting of the entire stand on the support blocks 14 permits the roll gap to be adjusted symmetrically about a constant pass-line, which can be maintained regardless of roll diameter; this is of importance in rod rolling and other tandem mill operations.

In the second place, the roll gap adjusting mechanisms (the screw-jacks 45-47 in FIGS. 4 and 5) being located in or on the support blocks 14 are divorced from the chocks 15 and 16, a feature unusual in prestressed mills. As a result the expense of having separate roll gap adjusting mechanisms on each spare chock for the stand is avoided and sealed roll gap adjusting mechanisms which do not have to be distributed at roll change may be employed.

In the third place, the roll gap adjusting mechanisms are subject to preload at all times with the result that all clearances are taken up and the overall dimensions alter little with rolling load; this is particularly important when operating with relatively light rolling loads, where conventional mills operate with a non-linear mill modulus curve.

In the fourth place, the support blocks 14 constitute mounting posts enabling guide equipment, coolant equipment and other stand furniture to be attached directly to the stand. This equipment has, of necessity, to be located in close proximity to the rolls and the only practical solution is to attach this equipment to the mill structure. If the mill structure consists entirely of an arrangement of chocks then at roll change time the complete mill has to be removed from the mill line. The operator must then be faced with the task of stripping this expensive and complicated equipment off the old stand and rebuilding onto the new stand, which is not really a practicable proposition if anything like a reasonable output on the mill is to be maintained, or having a duplicate set of equipment ready to build up a complete stand. As will be readily appreciated, this drawback is eliminated on the stands shown in the drawings as the aforementioned integral structure containing the roll gap adjusting mechanism can be rigidly and permanently attached to its foundations and it is left in situ in the mill line at roll change time complete with the stand furniture.

What I claim is:

1. A rolling mill stand having rolls carried at their ends in bearing chocks, fixed spacer blocks interposed between the bearing chocks at each end of the rolls and including adjustment means carried by each block to vary the eifective length thereof between the chocks, and means acting on the chocks at each end of the rolls to force the chocks into engagement with the blocks and to hold the checks to the blocks, the stand being solely supported by the blocks.

2. A rolling mill stand comprising rolls carried at their ends in T-shaped chocks, fixed supports at the ends of the rolls, each support comprising a pair of inwardly extending blocks which are interposed between the arms of the chocks, adjustment means carried by each block for varying the elfective length of the block between the chocks, and means acting on the checks at each end of the rolls to force the chocks into engagement with the blocks and to hold the checks to the blocks.

3. A rolling mill stand according to claim 1 in which the adjustment means for each block comprises a mechanical adjustment device interposed between each chock associated therewith and the adjacent block face.

4. A rolling mill stand according to claim 3 in which one at least of the adjustment devices of each chock is a wedge mechanism.

5. A rolling mill stand according to claim 1 in which the adjustment means for each block comprises a telescopic device supported by the block and engaging at opposite ends the co-operating checks and means for varying the length of the telescopic device symmetrically about a fixed midpoint.

6. A rolling mill stand according to claim 1 in which each chock engages the supporting blocks through bearing means permitting the chock to tilt on the blocks about an axis at right-angles to the roll axis.

7. A rolling mill stand according to claim 6 in which the bearing means are so arranged that the tilting axis intersects the roll axis.

8. A rolling mill stand according to claim 1 in which the means forcing the chocks into engagement with the blocks are hydraulic.

9. A rolling mill stand according to claim 1 in which the means forcing the chocks into engagement with the blocks comprise bolts arranged to hold the chocks together, each secured at one end in a chock of one roll and engaging a chock of the other roll through a piston and cylinder.

10. A rolling mill stand according to claim 9 in which the bolts pass through the chocks only.

11. A rolling mill stand according to claim 9 in which the bolts pass through the chocks and the blocks.

12. A four-high rolling mill stand according to claim 1 in which the bearing checks are those of the back-up rol'ls.

References Cited UNITED STATES PATENTS 3,217,525 11/1965 Howard 72-237 3,286,501 11/1966 Tracy 72237 2,774,263 12/1956 Leufven 72-238 CHARLES W. LANHAM, Primary Examiner B. J. MUSTAIKIS, Assistant Examiner 

